HUGE external interference!!!!

[Lesmana]

DEAR ALL EXPERTS,

PLEASE SHARE YOUR SUGGESTION / ANY DOC REGARDING:HOW TO REDUCE / ELIMINATE EXTERNAL INTERFERENCE ???

RECENTLY WE GOT EGSM (880 TO 885 MHZ) LICENSE AND DEPLOYED THE BAND IN OUR NETWORK. AFTER THAT WE GOT H-U-G-E EXTERNAL INTERFERENCE FROM THE LOCAL CDMA NETWORK.AS U PEOPLE KNOW THEIR BAND IS 1.25 MHz WIDE BAND AND ITS VERY CLOSE TO OUR 880 MHZ.

OUR EQUIPENT VENDOR IS HUAWEI.

PLEASE SUGGEST HOW TO TAKE CARE THIS ISSUE EXCEPT USING FILTER.


THANKS.

[melkaiy]

perform a band scan using spectrum analyzer.. kindly add reputaion thnks man

[Asif Ameer]

1st check the affected EGSM band though spectrum analyzer for example you are getting interference from 880 MHZ to 882MHZ band whereas from 882to 885 is normal. you can check external interference through 2 ways.
1st is directly connect spectrum analyzer with CDU port or Antenna port of each sector for observing all sector interference then you will realize that which sector has high interference.suppose Cell2 have strong interference then check cell 2 direction may be infront of cell 2 there will be CDMA site then need to change antenna direction or need to enhance guard band between EGSM and CDMA band.contact frequency allocation board.

2nd way is drive test with spectrum analyzer with yagi antenna for finding source of interference may be some Agencies using the frequency illegally.Which need to block complain Telecommunication authority.

If still you are confuse then add me on MSN at asifameer@hotmail.com

Wish you best of luck!
Pls add rep & thanks.

[harrypotter]

Asif,

Can you make a step by step procedure on how to do this?

[zeezzoo]

you can do spectrum scan by live monitoring in LMT . this is very much easier .
but you should have checked the band before you got the license . any way try not to use the interfered frequency till you settle down an agreement with cdma network operator , or you can try to shift the band you are using after coordinating with the legal authorities .

[Asif Ameer]

Please review attached template may be helpful for you with snap shot.

Dont forget to add rep & thanks.

Regards,

Asif Ameer

[tthach830]

Both of carrier can do downtilt or reduce power to reduce interference.

[tthach830]

you can do spectrum scan by live monitoring in LMT . this is very much easier .
but you should have checked the band before you got the license . any way try not to use the interfered frequency till you settle down an agreement with cdma network operator , or you can try to shift the band you are using after coordinating with the legal authorities .

I agreed with this. Coordinate with the other carrier and have an agreement. Most will be willing to work things out and avoid intereferene on each other netowkr. In our case, we had to reduce power and add downtilt.

[T_ADD]

DEAR ALL EXPERTS,

PLEASE SHARE YOUR SUGGESTION / ANY DOC REGARDING:HOW TO REDUCE / ELIMINATE EXTERNAL INTERFERENCE ???

RECENTLY WE GOT EGSM (880 TO 885 MHZ) LICENSE AND DEPLOYED THE BAND IN OUR NETWORK. AFTER THAT WE GOT H-U-G-E EXTERNAL INTERFERENCE FROM THE LOCAL CDMA NETWORK.AS U PEOPLE KNOW THEIR BAND IS 1.25 MHz WIDE BAND AND ITS VERY CLOSE TO OUR 880 MHZ.

OUR EQUIPENT VENDOR IS HUAWEI.

PLEASE SUGGEST HOW TO TAKE CARE THIS ISSUE EXCEPT USING FILTER.


THANKS.

you can also use a scanner and home in to the strong signal direction to eventually find the source of interference.

[Asif Ameer]

There are different ways for checking external interference.I would like to do following inorder to find out source of interference.

In my case,we were getting an interference at same EGSM band and we were getting an interference from 2 places.

1-Sea side or border of the country.
We found border interference just scan GSM/EGSM Network in your mobile at sea side and near to border.Go to mobile setting -Network-Search network manually.If found any other operator which is not allowed from Telecommunication Authority then make complain.



3-From CDMA BTS sites.
CDMA Network was affecting our band from 882 MHZ to 884 MHZ band due to 2MHZ guard band between CDMA and EGSM was not sufficient because CDMA Network was using very old equipment which was generating harmonics.When we ask CDMA operator then they didn't accept that interference coming from CDMA sites After negociation with them we agreed for testing 1 BTS site where both network site was near togethor and selected remote area for testing where only one side of both network was deployed.

Testing Procedure:
1-1st check interference by using spectrum analyzer at both Network antenna port of cell1 ,cell2 and cell3. Here you will getting high interference.

2-Now turned off CDMA BTS and wait for 2 minutes becasue energy take time to dissipate after some time you will see that There is no interference at your BTS antenna port of cell1,cell2 and cell3.Therefore through this procedure you will resolve your problem

Wish you best of luck

[melkaiy]

sirs' u should perform a band scan .... u can determine if there is interference in gsm if the message says: intra freq ho - which means there is ho in same freq. and the result is block call or rach error. perform a band scan every 30 deg in the tower. trace every strength.. as u get nearer in the source.

[justdream]

Check/ sort your TOP External interference cells,
then do Query Freq. scan from Huawei Web LMT to get output: which freq, in your band are clean, impacted

accordingly, you could optimize your assgined freq.

[louvre]

Check/ sort your TOP External interference cells,
then do Query Freq. scan from Huawei Web LMT to get output: which freq, in your band are clean, impacted

accordingly, you could optimize your assgined freq.

adding some more suggestion to the one above is:

1. check if the whole band is affected or specific frequency are affected.

for specific band many of the suggestion might be true and you may have to work to eliminate the probable causes.

2. if the whole band or most of the band is affected then / area is affected it is quite possible that there might be external source of interference and that interference can be anything from rouge WCDMA/ frequency/ jammer(channel pass/ band pass).

in case of jammer depending on the type few channels or whole band can be screwed... in which case you may have take the matter up with authorities who have installed it in the first place!!

[rocketfire]

in addition, other things that should help you with this kind of problems are:
-have a map with all sites located and identify the sectors affected.
-check all statistic information available.
-if you detect something on the spectrum analyzer save the picture on disc and take notes (day and time) on every change, remember that if you will use a provider to do the tests on field the cost will increase every day.
-when you turn OFF the sectores to identify the interference source try to do it at low traffic hours and at the end don´t forget turn ON the sectors again.
-review that your spectrum analyzer has been calibrated.